General mechanisms of drought response and their application in drought resistance improvement in plants

Plants often encounter unfavorable environmental conditions because of their sessile lifestyle. These adverse factors greatly affect the geographic distribution of plants, as well as their growth and productivity. Drought stress is one of the premier limitations to global agricultural production due to the complexity of the water-limiting environment and changing climate. Plants have evolved a series of mechanisms at the morphological, physiological, biochemical, cellular, and molecular levels to overcome water deficit or drought stress conditions. The drought resistance of plants can be divided into four basic types-drought avoidance, drought tolerance, drought escape, and drought recovery. Various drought-related traits, including root traits, leaf traits, osmotic adjustment capabilities, water potential, ABA content, and stability of the cell membrane, have been used as indicators to evaluate the drought resistance of plants. In the last decade, scientists have investigated the genetic and molecular mechanisms of drought resistance to enhance the drought resistance of various crops, and significant progress has been made with regard to drought avoidance and drought tolerance. With increasing knowledge to comprehensively decipher the complicated mechanisms of drought resistance in model plants, it still remains an enormous challenge to develop water-saving and drought-resistant crops to cope with the water shortage and increasing demand for food production in the future.     

Naturally occurring heterocycles inducing drought resistance in plants

Summary During screening of animal metabolites which induce drought resistance in plants, two diketopiperazines, cyclo(L-Hyp-L-Pro) (1) and cyclo(L-Hyp-L-Leu) (2), emerged as effective. When rice seeds were pretreated with the cyclic dipeptides (1 and2) during their germination period, the resulting seedlings showed significant resistance to water-stress caused by 0.5–1.5% NaCl solution or 2.5–5.0% mannitol solution.     

Enzymatic synthesis and destruction of carotenoids in mango extracts

Zusammenfassung Eine Biosynthese von Carotin lässt sich in zellfreien karotenoidhaltigen Extrakten reifer Mangofrüchte bei Gegenwart von Glucose oder Azetat beobachten. Dabei zeigt sich gleichzeitig eine Abnahme der Karotenoide.     

Disposition of carotenoids in the blue goose barnacleLepas fascicularis

Zusammenfassung Die blauen ozeanischen Cirripedien,Lepas fascicularis, speichern Karotinoide in Eiern, Eingeweiden und den meisten übrigen Geweben in den folgenden ungefähren Konzentrationen: 5:2:1 mg/100 g. In jeder Art von Gewebe ist Astaxanthin das Hauptkarotinoid, welches meist in Form des blauen Chromproteins vorliegt. Kleinere Mengen von Karotin und etwas mehr Xanthophylle kommen in den Eingeweiden, nicht aber in den reifen Eiern vor.

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Contribution from the Scripps Institution of Oceanography. This research was supported by Research Grant No. GB-5332X from the National Science Foundation. We are indebted also toJoanne Rhoads andP. Wiebe for donating some of the fresh barnacle specimens, and to Dr.W. A. Newman for his help and information concerning the biology and dissection of this barnacle.     

Electrolytic behaviour of some carotenoids in strongly acid media

Zusammenfassung Carotinoide und Carotinoid-Epoxyde bilden mit verschiedenen Säuren und Salzen intensiv blau gefärbte Produkte, deren Natur unbekannt ist. Das elektrolytische Verhalten dieser Stoffe wird untersucht, und es wird festgestellt, dass die Wanderungsrichtung in hohem Mass davon abhängt, ob die Behandlung der Carotinoide mit Säuren in wässeriger oder in wasserfreier alkoholischer Lösung vorgenommen wurde.     

LSD induced chlorophyll mutations in barley

Summary In earlier reports, LSD was found to induce extensive chromosomal aberrations in barley. With the same dose it is now observed that LSD is potent in the induction of chlorophyll mutations. This may be the first evidence that the drug induces gene mutations in plants.Acknowledgent. We are grateful to Dr H.K. Jain, Indian Agricultural Research Institute, for his interest and guidance.     

Rapid preparation of pure chlorophyll a

Summary Very pure chlorophyll a has been obtained from blue-green algae by a simple precipitation procedure. Its purity is at least equal to that of chlorophyll a obtained from spinach by conventional chromatography.Acknowledgments. This work was supported by the Fonds zur Förderung der wissenschaftlichen Forschung of the Republic of Austria. We thank Dr H. Springer-Lederer for helpful comments and Prof. E. Broda for his interest.     

Mechanism of potassium deficiency-induced retardation of chlorophyll biosynthesis in Zea mays

Summary Potassium deficiency decreased the formation of protochlorophyll and retarded the rate of transformation of protochlorophyll to chlorophyll in maize seedlings.     

The interaction of a gibberellin and a kinin in the control of chlorophyll synthesis

Resumé La promtion synergétique et l'inhibition de la synthèse de la chlorophylle par la gibberelline (GA₃) et par la 6-benzylaminopurine (6-BAP) de concentrations diverses, fut observée. L'augmentation de la concentration de 6-BAP réduisit la concentration de GA₃ nécessaire pour obtenir la promotion maximum.     

On the location of the tetrapyrrole macrocycle of chlorophyll a in phospholipid vesicles and in hexadecane

Summary The state of chlorophyll a in phosphatidylcholine vesicles was examined. The results indicate that the chlorophylls are present in monomeric form. A kinetic study of chlorophyll reactions with K₂S₂O₈ and piperidine showed that these substances react with the porphyrin rings of pigments located on both vesicle faces, most probably within the polar headgroup region.Acknowledgments. This work was supported by the Research Committee and the Biophysics Research Group, University of Québec at Trois-Rivières.     

Structural characteristics of the carotenoids binding to the blue carotenoprotein fromProcambarus clarkii

Summary A blue carotenoprotein from the crayfishProcambarus clarkii was extracted and purified. This carotenoprotein contains the carotenoid astaxanthin as a prosthetic group. In the present work we have identified by reconstitution, after removing the native carotenoid, some characteristics of the carotenoids that could bind to the apoprotein. The carotenoid must have two oxo groups at positions 4, 4 and two hydroxyl groups at positions 3, 3 the hexagonal or pentagonal end structure being indifferent. It has been proved that changes in the polyene chain structure such as triple bonds destroy this binding capacity.     

The presence of carotenoids in eggs deposits of theChironomus annularius meig (Diptera: Chironomidae)

Résumé A l'aide de la Chromatographie sur colonne et sur couche fine, les auteurs ont effectué la séparation des caroténoïdes des ufs deChironomus annularius Meig (Diptera: Chironomidae). Ces recherches ont attesté la présence du -carotene, de l'échinénone, de la cryptoxanthine et de la lutéine.     

Induction of chromosome aberrations and chlorophyll mutations in plants by methylisocyanate (MIC) gas

Summary Seeds ofSolanum surattense Burm. f. collected from areas of Bhopal (India) affected by methylisocyanate gas showed chromosome aberrations in root cells, and growth retardation and chlorophyll mutation of seedlings, the frequencies of which varied from one locality to another.